The General Motors boss Fritz Henderson was supposed to be keynote speaker this morning at the opening of the Los Angeles motor show. At least, that was the plan - until he abruptly resigned, at the behest of the company's board, on Tuesday.

GM has been tight-lipped, to put it mildly, about the reasons for Henderson's departure. So naturally, reporters were eager to hear from the man hastily put up to take the stage instead - GM's vice-president, Bob Lutz.

"I know you all would like to know the true inside story of what transpired at General Motors yesterday," Lutz quipped to his audience, according to the Detroit News. "I'm not going to give it to you. I will definitely be Mr. Teflon when it comes to the Fritz question. I will exercise enormous skill in the non-answering of your questions."

Lutz did say he was "genuinely saddened" by Henderson's departure and, slightly more tendentiously, described the timing as "inopportune". He added: "You can dwell on what happened and let it get you down, that's certainly not the way I was trained in the Marine Corps."

The bare bones of the discontent that led to Henderson's ousting are becoming clearer. Directors, led by chairman Ed Whitacre, weren't happy with progress in reviving GM's crucial US sales or in transforming the company's ponderous culture. They took issue with Henderson's handling of the struggling Swedish brand Saab. Tension has been evident since the board over-ruled Henderson's plan to sell GM's European division, Opel and Vauxhall, in November.

A GM careerist of 25 years' standing, Henderson might be entitled to feel a bit shabbily treated at such an undignified exit. The White House felt moved to praise him today - President Obama's spokesman, Robert Gibbs, told reporters in Washington that Henderson had "done a good job in a period of transition" and insisted that the Treasury had nothing to do with his departure.

Given that the US public owns a majority stake in GM, there's an argument that the company needs to be a little more accountable than the two-minute statement on Henderson's departure read out at a press conference on Tuesday evening. After reading his script, Whitacre turned on his heels and walked out of the room without taking questions.

In the semi-public world of social networking, somebody thinks they know what really happened. A person with a profile under the name of Henderson's daughter, Sarah Henderson, posted an expletive-riddled rant on GM's Facebook page taking issue with the company's line of a mutually agreed departure.

"HE FUCKING GOT ASKED TO STEP DOWN ALL OF YOU FUCKING IDIOTS," said the post, entirely in capital letters. "IM FRITZ'S FUCKING DAUGHTER, AND HE DID NOT FUCKING RESIGN."

The post went on to express a degree of, shall we say, frustration, at Whitacre and to wish GM the worst of all prospects for the future.

Whether this was genuinely Henderson's daughter is unclear - it could be a prankster. The post has been removed and, as the Huffington Post points out, a search under the name "Sarah Henderson" brings up 339 pages of people on Facebook. Maybe Fritz himself will spill the beans someday soon.